Thousands of mortgage holders are facing huge rises in their monthly repayments due to a banking error.

Customers of the Yorkshire and Clydesdale Bank have been left with a shortfall on their variable rate mortgages after the bank miscalculated their monthly repayments.

The bank said 18,000 customers had paid less than the contractual minimum monthly repayments needed to pay their mortgage within the agreed term.

It said historically low Bank of England interest base rates had exacerbated the problem.

Affected customers have now been asked to pay the correct monthly amount, plus an additional monthly sum to meet the shortfall.

While about half of the customers – some 9,000 people – have been asked to pay an increase of less than £25 a month, the rest face soaring repayments of up to £300 a month.